Abstract: Disclosed is an engine surge avoidance system and method which adapts the acceleration schedules (i.e., P2.5 bleed valve and NDOT) to prevent engine surge events from occurring while minimizing reductions in engine response time. The surge avoidance system and method disclosed herein achieves this goal by adapting both the NDOT and the P2.5 bleed schedules in an optimum fashion.

Abstract: A fuel metering unit including a pump having a rotor with a plurality of slots. The pump also includes a pivotally movable cam ring coaxially arranged with respect to the rotor. Vanes are slideably disposed in the slots for maintaining contact with the cam ring during movement thereof. A servovalve has a motor and nozzles operatively connected to the pump such that increased flow through the first nozzle pivots the ring of the pump toward maximum while increased flow through the second nozzle pivots the ring toward minimum. An arm extends between the nozzles for varying fluid flow therethrough. The arm couples to the motor such that the motor moves the arm. A flow meter connects to the pump and an end of the arm for applying a force against the arm to assist in maintaining position of the arm.

Abstract: The subject invention is directed to a new and useful method of detecting in-range engine sensor faults for a gas turbine engine associated with a helicopter. The method includes the steps of computing engine shaft horsepower for a plurality of engine sensor, computing a first mean horsepower from the plurality of engine sensors, computing the horsepower deviation from the first mean horsepower for each engine sensor, computing a horsepower deviation ratio for each engine sensor relative to all other engine sensors, disabling the engine sensor with the largest deviation from the first mean horsepower, computing a second mean horsepower, computing the horsepower deviation from the second mean horsepower for each engine sensor, re-computing the horsepower deviation ratio for each engine sensor relative to all other engine sensors, comparing the horsepower deviation ratios to predefined limits, and declaring a sensor fault if the horsepower deviation ratio for an engine sensor exceeds a predefined limit.

Abstract: Disclosed is a system and method for monitoring the vibration levels of gas turbine engines. The vibration monitoring system acquires vibration data from an engine, and processes the data with advanced algorithms to determine engine component health, both in a diagnostic and prognostic fashion. The method includes the steps of measuring an operating parameter and a corresponding set of vibration amplitudes for a plurality of rotating component during a period of operation and normalizing the set of measured vibration amplitudes based on established amplitude limits. The set of normalized amplitude data points are stored in parameter-based data blocks, which extend over a predetermined range of the operating parameter. For each data block, a time period remaining to reach the established amplitude limits is estimated based on changes in the normalized amplitude data points stored in the data blocks.

Abstract: A control system is disclosed for optimizing the transient response of a gas turbine engine by controlling the variable positioning of compressor inlet guide vanes. The system employs a normal mode schedule which schedules relatively closed inlet guide vane settings at low compressor speeds and relatively open inlet guide vane settings at high compressor speeds. The system further employs an alternate mode schedule that schedules inlet guide vane settings that are more closed at low compressor speeds than those scheduled by the normal mode schedule. Control logic is provided for rapidly moving the inlet guide vanes from the more closed settings of the alternate mode schedule to settings which are more open than those which are schedule by the normal mode schedule, during an acceleration from low engine power levels. The control logic is further configured to command the inlet guide vanes back to the normal mode schedule as the acceleration nears completion.

Abstract: A control system is disclosed for optimizing the transient response of a gas turbine engine by controlling the variable positioning of compressor inlet guide vanes. The system employs a normal mode schedule which schedules relatively closed inlet guide vane settings at low compressor speeds and relatively open inlet guide vane settings at high compressor speeds. The system further employs an alternate mode schedule that schedules inlet guide vane settings that are more closed at low compressor speeds than those scheduled by the normal mode schedule. Control logic is provided for rapidly moving the inlet guide vanes from the more closed settings of the alternate mode schedule to settings which are more open than those which are schedule by the normal mode schedule, during an acceleration from low engine power levels. The control logic is further configured to command the inlet guide vanes back to the normal mode schedule as the acceleration nears completion.

Abstract: A power turbine speed control system for a helicopter is disclosed which includes components for generating a power turbine speed signal based upon a demanded rotor speed, a high-order filter for filtering the power turbine speed signal by effectuating a rapid attenuation of main and tail rotor torsional frequencies in the power turbine speed signal without compromising phase at low frequencies, and a governor for providing isochronous power turbine speed and rotor speed control based upon the filtered power turbine speed signal.

Abstract: Fuel control systems for use with a gas turbine engines which accounts for real-time thermodynamic engine effects when attempting to match or track the NDOTActual rate to the NDOTDemand rate. The fuel control system includes a mechanism for measuring several engine operating parameters and a mechanism for determining an initial engine fuel demand based on the measured engine operating parameters. The control system further includes a mechanism for estimating, during engine operation and based on the measured operating parameters, the amount of heat transferred between fuel combustion gases and the engine metal and estimating an effective fuel flow adjustment based therefrom. The control system disclosed herein also includes a mechanism for determining a final engine fuel demand based on the initial predicted engine fuel demand and the estimated effective fuel flow adjustment.

Abstract: A vane pump is disclosed for use with gas turbine engines adapted and configured to provide a failure mode similar to that of a traditional gear pump. The vane pump includes a pump housing, a cam member, a cylindrical rotor member and a mechanism for communicating a high pressure fluid from the discharge arc region to the inlet arc region when the tip surface of each vane element has experienced a predetermined amounted of wear so as to prevent pump startup. The wearing of the tip surface of each vane element resulting from the slideable engagement with the circumferential surface of the pumping cavity.

Abstract: A vane pump is disclosed for use with gas turbine engines which has pressurized fluid supplied to the undervane portion of the vane elements to balance the forces imparted thereon. The vane pump includes a pump housing, a cam member, a cylindrical rotor member and a chamber. The chamber is defined within the housing and positioned for fluid communication with the undervane portion of each vane element to provide a desired pressure thereto. The chamber is in fluid communication with a first pressure source and a second pressure source, wherein the first pressure source is associated with the discharge arc segment of the pumping cavity, and the second pressure source is associated with the inlet arc segment of the pumping cavity.

Abstract: A fuel metering unit including a pump having a rotor with a plurality of slots. The pump also includes a pivotally movable cam ring coaxially arranged with respect to the rotor. Vanes are slideably disposed in the slots for maintaining contact with the cam ring during movement thereof. A servovalve has a motor and nozzles operatively connected to the pump such that increased flow through the first nozzle pivots the ring of the pump toward maximum while increased flow through the second nozzle pivots the ring toward minimum. An arm extends between the nozzles for varying fluid flow therethrough. The arm couples to the motor such that the motor moves the arm. A flow meter connects to the pump and an end of the arm for applying a force against the arm to assist in maintaining position of the arm.